While the accessory adds a good amount of battery life to your iPhone 6 and 6s models and integrates with iOS to show a battery status icon, a number of complaints have surfaced about its “hunchback” design, complete with a protruding battery on the back.

“The battery juts out as if your phone will soon give birth to a rectangular alien,” says Joanna Stern of the Wall Street Journal in her review, which may just be accurate.

The iPhone 6s Smart Battery Case also arrives in two color options: charcoal gray and white, and the white seems to collect dirt like nobody’s business according to Stern.

Other problems include the fact that while Apple’s 3.5mm earbuds fit perfectly into the headphone jack, some headphone jacks, such as those found on the Beats Solo HD, don’t.

Another major problem that’s been noticed is that the device doesn’t power the iPhone 6s all the way. And while jumping from a completely depleted iPhone battery to 83 percent is decent, it’s still not the 100 percent people might expect.

Still, the unit did appreciably extend the iPhone 6s’ battery life, adding several hours to talk time and Internet usage.

The criticism was also harsh over at The Verge, which makes some good points about its design, compliments the unit’s integration of the Lightning port and charge status, but also brings up the fact that this is clunkier than what’s typically expected of Apple:

The iPhone 6s Smart Battery Pack may become infamous for a variety of reasons. First, this could serve as an admission of the iPhone 6s’ relatively poor battery life. Second, the design doesn’t seem worthy of Apple and the fact that this came out of Jony Ive’s labs shows that something is askew here. Finally, at $99, this seems like a pricey solution to something that a Mophie Juice Pack or other device can do that much cheaper.

Apple hasn’t had that many black eyes during Tim Cook’s reign, but this could be one of them.